2 # The stub may be linked into the kernel proper or into a separate boot binary,
3 # but in either case, it executes before the kernel does (with MMU disabled) so
4 # things like ftrace and stack-protector are likely to cause trouble if left
5 # enabled, even if doing so doesn't break the build.
7 cflags-
$(CONFIG_X86_32
) := -march
=i386
8 cflags-
$(CONFIG_X86_64
) := -mcmodel
=small
9 cflags-
$(CONFIG_X86
) += -m
$(BITS
) -D__KERNEL__
$(LINUX_INCLUDE
) -O2 \
10 -fPIC
-fno-strict-aliasing
-mno-red-zone \
13 cflags-
$(CONFIG_ARM64
) := $(subst -pg
,,$(KBUILD_CFLAGS
))
14 cflags-
$(CONFIG_ARM
) := $(subst -pg
,,$(KBUILD_CFLAGS
)) \
15 -fno-builtin
-fpic
-mno-single-pic-base
17 cflags-
$(CONFIG_EFI_ARMSTUB
) += -I
$(srctree
)/scripts
/dtc
/libfdt
19 KBUILD_CFLAGS
:= $(cflags-y
) -DDISABLE_BRANCH_PROFILING \
20 $(call cc-option
,-ffreestanding
) \
21 $(call cc-option
,-fno-stack-protector
)
27 lib-y
:= efi-stub-helper.o
29 # include the stub's generic dependencies from lib/ when building for ARM/arm64
30 arm-deps
:= fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c
sort.c
32 $(obj
)/lib-
%.o
: $(srctree
)/lib
/%.c FORCE
33 $(call if_changed_rule
,cc_o_c
)
35 lib-
$(CONFIG_EFI_ARMSTUB
) += arm-stub.o fdt.o string.o \
36 $(patsubst %.c
,lib-
%.o
,$(arm-deps
))
38 lib-
$(CONFIG_ARM
) += arm32-stub.o
39 lib-
$(CONFIG_ARM64
) += arm64-stub.o
40 CFLAGS_arm64-stub.o
:= -DTEXT_OFFSET
=$(TEXT_OFFSET
)
43 # arm64 puts the stub in the kernel proper, which will unnecessarily retain all
44 # code indefinitely unless it is annotated as __init/__initdata/__initconst etc.
45 # So let's apply the __init annotations at the section level, by prefixing
46 # the section names directly. This will ensure that even all the inline string
47 # literals are covered.
48 # The fact that the stub and the kernel proper are essentially the same binary
49 # also means that we need to be extra careful to make sure that the stub does
50 # not rely on any absolute symbol references, considering that the virtual
51 # kernel mapping that the linker uses is not active yet when the stub is
52 # executing. So build all C dependencies of the EFI stub into libstub, and do
53 # a verification pass to see if any absolute relocations exist in any of the
56 extra-
$(CONFIG_EFI_ARMSTUB
) := $(lib-y
)
57 lib-
$(CONFIG_EFI_ARMSTUB
) := $(patsubst %.o
,%.stub.o
,$(lib-y
))
59 STUBCOPY_FLAGS-y
:= -R .debug
* -R
*ksymtab
* -R
*kcrctab
*
60 STUBCOPY_FLAGS-
$(CONFIG_ARM64
) += --prefix-alloc-sections
=.init \
61 --prefix-symbols
=__efistub_
62 STUBCOPY_RELOC-
$(CONFIG_ARM64
) := R_AARCH64_ABS
64 $(obj
)/%.stub.o
: $(obj
)/%.o FORCE
65 $(call if_changed
,stubcopy
)
67 quiet_cmd_stubcopy
= STUBCPY
$@
68 cmd_stubcopy
= if
$(OBJCOPY
) $(STUBCOPY_FLAGS-y
) $< $@
; then \
69 $(OBJDUMP
) -r
$@ | grep
$(STUBCOPY_RELOC-y
) \
70 && (echo
>&2 "$@: absolute symbol references not allowed in the EFI stub"; \
71 rm -f
$@
; /bin
/false
); else /bin
/false
; fi
74 # ARM discards the .data section because it disallows r/w data in the
75 # decompressor. So move our .data to .data.efistub, which is preserved
76 # explicitly by the decompressor linker script.
78 STUBCOPY_FLAGS-
$(CONFIG_ARM
) += --rename-section .data
=.data.efistub
79 STUBCOPY_RELOC-
$(CONFIG_ARM
) := R_ARM_ABS